The Ursula deck contains Entangled cards These are essentially new cards, with new abilities, art, a very different decoration, and the new Entangled keyword
JS You have been collecting for almost 40 years so you have seen a lot of innovation in the Hobby over the years
But there's also a rule that says that the card supercedes the rulebook
Sideboarding is a complex topic that could be the focus of an entire article, but if you have never done it before, I'll outline two simple sideboarding methods here
From the split-ness of Spite // Malice to the gold of Lim-Dul's Vault to the hybrid of Dimir Guildmage, there are a number of powerful and iconic cards in this color
If this card is Normal or Special Summoned: You can send the top 3 cards of either player's Deck to the GY